Marshall, 28, later set fire to the bungalow in Northolt to cover up the murder.

Mr Fasoli's death was thought to be an accident until his nephew found CCTV of the murder stored on his hard drive.

Image copyrightPeter Fasoli/FacebookImage caption
Peter Fasoli's death was filmed on a computer in his north London bungalow

The harrowing footage found by Christopher Murgatroyd showed the victim bound and naked on his bed, begging for his life and complaining he could not breathe before Marshall wound cling film around his head.

The trial had heard how former male escort Marshall stalked victims on gay dating website Badoo.

He went to Mr Fasoli's flat in Northolt, west London, on the evening of 6 January 2013 on the pretext of bondage sex, dressed as a law enforcement agent complete with handcuffs, police utility belt, holster and latex gloves.

He "arrested" Mr Fasoli "for being a spy" and during his fake interrogation he threatened to cut his tongue with a large hunting knife to extract his PIN numbers.

Image copyrightPAImage caption
It was originally believed Mr Fasoli died in a fire in his bungalow

'Tortured while we were sleeping'

After setting the flat alight, Marshall used Mr Fasoli's bank cards to buy a flight to Rome, where he continued his violent spree, killing a second man and attempting to murder a third within weeks.

He evaded justice for Mr Fasoli's death for nearly two years.

Commenting on the attack, neighbour Layla Light said: "We was all very shocked because he [Mr Fasoli] kept himself to himself, no-one really knew him, and we knew he had a lot of electrical equipment so we just assumed it was an electrical fire.

"It's quite scary because it's come out that the guy has killed other people and he died and was tortured to death while we were sleeping."

Image copyrightJulia QuenzlerImage caption
Marshall showed no reaction as the verdicts were delivered

Marshall, from East Ham, east London, who is already serving 16 years for the attacks in Italy, showed no reaction as the verdicts were delivered on Wednesday.

The case has raised questions about why the original investigation failed to spot that Mr Fasoli's bank cards were used after his death or that his murder was caught on CCTV.

Human rights campaigner Peter Tatchell likened the case to that of gay serial killer Stephen Port and said he was "shocked and surprised" the Independent Police Complaints Commission was not investigating.

Mr Tatchell said: "This case has echoes of the serial killings by Stephen Port. There appears to have been missed opportunities and serious failings of the police investigation."

Image copyrightPAImage caption
After footage emerged of Mr Fasoli's killing, a pathologist found that asphyxiation also contributed to his death

'Pleasure from dominating'

After the footage emerged of Mr Fasoli's killing, a pathologist found that asphyxiation also contributed to his death, although he was still alive but unconscious when the fire started.

While on the run in Italy, Marshall strangled Vincenzo Iale, 67, with electrical flex in his flat and made off with his bank card and car on 26 January, 2013.

Just over a week later, he posed as a British embassy official, armed with a holster, utility belt, pistol, pepper spray and truncheon, when he met Umberto Gismondi, 54, for sex.

He bound and gagged Mr Gismondi as he demanded cash but fled after the victim managed to alert his neighbours.

In July 2014, Marshall was found guilty of murder and attempted murder and was jailed for 16 years.

Under cross-examination on Wednesday, he admitted he got pleasure from dominating naked men while pretending to be a policeman.

Asked by Judge Nicholas Hilliard QC if he had been trying to "terrify" Mr Fasoli, he said: "Yes, my lord, with the prospect of torture."

Marshall was remanded in custody on Wednesday to be sentenced on a later date.

How a murderer evaded justice for years

7 January 2013: Mr Fasoli is found dead at his home in Rubens Road, Northolt

7/8 January: £780 is withdrawn from his bank account. Marshall books a return flight from Gatwick to Rome using Mr Fasoli's bank card

11 January: Marshall boards the flight, but does not get on the return flight on 17 January

3 February: Italian police find the body of Vincenzo Iale, 67, in his home in Torvaianica on the outskirts of Rome. He was naked lying on the floor with an electrical flex around his neck. The hard drive of his computer had been removed and his car stolen. It is established he died on the night of 26/27 January. Days afterwards his bank card is used to make cash withdrawals

The same day: Marshall meets 54-year-old man Umberto Gismondi for sex. He arrives carrying a pistol, pepper spray can and telescopic truncheon and false identification suggesting he worked for the British embassy. He binds and gags Mr Gismondi, assaults him and demands money, bank cards and pin numbers. Mr Gismondi's shouting alerts neighbours and Marshall fled the scene, taking the victim's mobile phone with him

16 August: Inquest recorded verdict of accidental death into Mr Fasoli's death. Fire investigators conclude the fire had most likely been caused by a faulty LED falling from a ceiling fitting on to bedding which was highly flammable

9 July 2014: Marshall convicted by an Italian court of the murder of Mr Iale and attempted murder of Mr Gismondi. He is sentenced to 22 years